ZeroRPC for node.js

ZeroRPC for Python was posted a few months ago. For reference, here's the discussion: http://news.ycombinator.com/item?id=3761954

Is the ZeroRPC protocol documented anywhere?

I settled on using ZeroMQ + MessagePack to glue together my Python, Ruby, and C++ components, but haven't yet decided whether to use an existing RPC protocol or roll my own. ZeroRPC looks like a good candidate.